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Oriana Simonetti *, Guendalina Lucarini , Oscar Cirioni , Antonio Zizzi , Fiorenza Orlando , Mauro Provinciali , Roberto Di Primio , Andrea Giacometti , Annamaria Offidani a Department of Dermatology, Universita Politecnica delle Marche, Ancona, Italy Department of Clinic and Molecular Sciences – Histology, Universita Politecnica delle Marche, Ancona, Italy c Institute of Infectious Diseases and Public Health, Universita Politecnica delle Marche, Ancona, Italy d Institute of Pathology, Universita Politecnica delle Marche, Ancona, Italy Experimental Animal Models for Aging Unit, Scientific Technological Area, I.N.R.C.A., I.R.C.C.S., Ancona, Italy

The therapeutic efficacies of three polycationic peptides selected among the class of the magainins (magainin I, magainin II, and magainin II amide), alone and combined with piperacillin, were investigated in a rat model of septic shock. Rats were given an intraperitoneal injection of 2 × 1010CFU ofEscherichia coliand randomized to receive intraperitoneally isotonic sodium chloride solution, 60 mg of piperacillin per kg of body weight, and 1 mg of each magainin per kg alone and combined with 60 mg of piperacillin per kg. The main outcome measures were bacterial growth in abdominal exudate and plasma, endotoxin and tumor necrosis factor alpha (TNF-α) concentrations in plasma, and lethality. Treatments with the magainins achieved significant reductions of bacterial growth and plasma endotoxin and TNF-α concentrations. In general, treatments with the combinations of magainins and piperacillin demonstrated the highest efficacies.

Background. A rat model was used to investigate the efficacy of a polycationic peptide, the polymyxin-like ranalexin, in the prevention of lethality in a rat model of septic shock. The effect of ranalexin was compared with those of polymyxin B and imipenem. Methods. Adult male Wistar rats (weight range: 250–300 g) were used for all the experiments. The study included five groups: an uninfected control group C 0 , an untreated control group C 1 , and three drug-treated groups that received 1 mg/kg ranalexin (group 2), 20 mg/kg imipenem (group 3), and 3 mg/kg polymyxin B (group 4). Rats, with the exception of the uninfected control group (C 0 ), were given an intraperitoneal injection of 2 × 10 10 colony-forming units of Escherichia coli . Each group included 15 animals. Bacterial growth in abdominal exudate and plasma; endotoxin and tumor necrosis factor α (TNF-α) concentrations in plasma, and mortality were evaluated. Results. Results were evaluated 48 h after inoculation. Ranalexin, imipenem, and polymyxin B significantly reduced the lethality (survival was 93.3, 80.0, and 93.3%, respectively) and the growth of E. coli both in abdominal fluid and plasma compared with saline treatment. Ranalexin showed higher antimicrobial activity than polymyxin B and imipenem and, at the same time, exhibited an antiendotoxin activity similar to that of polymyxin B (≤0.015 EU/mL). Finally, ranalexin and polymyxin B significantly reduced plasma TNF-α levels (≤4 pg/mL). Conclusion. Monodose ranalexin treatment prevents bacterial growth, endotoxemia, and mortality in rats with septic shock.

A rat model was used to investigate the efficacy of mupirocin in the prevention of vascular prosthetic graft infections. The effect of mupirocin-soaked Dacron was compared with the effect of rifampin-soaked, collagen-sealed Dacron in the rat model of graft infection caused by methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus . Graft infections were established in the back subcutaneous tissue of 195 adult male Wistar rats by implantation of 1-cm 2 Dacron prostheses followed by topical inoculation with 5 × 10 7 colony-forming units of S. aureus . The study included a control group (no graft contamination), two contaminated groups that did not receive any antibiotic prophylaxis, two contaminated groups in which perioperative intraperitoneal amoxicillin clavulanate prophylaxis (50 mg/kg) was administered, four contaminated groups that received mupirocin- or rifampin-soaked graft, and four contaminated groups that received mupirocin- or rifampin-soaked graft and perioperative intraperitoneal amoxicillin clavulanate prophylaxis (50 mg/kg). The grafts were sterilely removed 7 days after implantation and the infection was evaluated by using sonication and quantitative agar culture. Data analysis showed that the efficacy of mupirocin against both strains was significantly different from that of the untreated control. In addition, mupirocin was more effective than rifampin against the methicillin-resistant strain. Finally, only the combination of mupirocin and amoxicillin clavulanate produced complete suppression of growth of all strains.

A rat model was used to investigate the efficacy of mupirocin in the prevention of vascular prosthetic graft infection due to Staphylococcus epidermidis strains with different susceptibility patterns (methicillin susceptible, methicillin resistant, and with intermediate resistance to vancomycin). The effect of mupirocin-soaked Dacron was compared to that of perioperative intraperitoneal prophylaxis with vancomycin. Graft infections were established in the back subcutaneous tissue of adult male Wistar rats by implantation of Dacron prostheses (1 cm 2 ) followed by topical inoculation with 5 × 10 7 CFU of one staphylococcal strain. The study included a control group (no graft contamination), three contaminated groups that did not receive any antibiotic prophylaxis, three contaminated groups that received mupirocin-soaked grafts, three contaminated groups in which perioperative intraperitoneal vancomycin prophylaxis (10 mg/kg of body weight) was administered, and three contaminated groups that received mupirocin-soaked grafts and perioperative intraperitoneal vancomycin prophylaxis (10 mg/kg). The grafts were sterilely removed 7 days after implantation, and the infection was evaluated by using sonication and quantitative agar culture. Data analysis showed the efficacy of mupirocin against all three strains, with growth of the strains in treated rats significantly different than that in the untreated control. In addition, mupirocin was more effective than vancomycin against the strain with intermediate susceptibility to the glycopeptide. Finally, the combination of mupirocin and vancomycin produced complete suppression of the growth of all of the strains.

Objective: The purpose of this study was to investigate the efficacy of temporin A as a prophylactic agent in a rat model of vascular graft infection from methicillin sodium-susceptible and methicillin sodium-resistant Staphylococcus epidermidis . Methods: The prospective, randomized, controlled animal study set in a research laboratory in a university hospital used 280 adult male Wistar rats (weight range, 280 to 350 g). Graft infections were established in the back subcutaneous tissue of rats with implantation of 1-cm 2 sterile Dacron grafts followed by topical inoculation with 2 × 10 7 colony-forming units of S epidermidis . The study for each staphylococcal strain included: one control group (no graft contamination), one contaminated group that did not receive any antibiotic prophylaxis, one contaminated group that received temporin A-soaked graft, two contaminated groups that received perioperative intraperitoneal cefazolin (30 mg/kg) or vancomycin hydrochloride prophylaxis (10 mg/kg), and two contaminated groups that received temporin A-soaked graft and perioperative intraperitoneal cefazolin (30 mg/kg) or vancomycin hydrochloride (10 mg/kg) prophylaxis. All grafts were explanted at 7 days after implantation. The main outcome measure was quantification of bacterial contamination. Results: Overall, the perioperative prophylaxis based on soaked grafts was not significantly different to that of parenteral vancomycin hydrochloride. Only the combination between temporin A and vancomycin hydrochloride produced a complete bacterial inhibition for both strains. Conclusion: Temporin A showed a similar antibacterial in vitro activity against the two different strains. The in vivo results suggest its potential use in providing prophylaxis to direct graft contamination when used in combination with parenteral vancomycin hydrochloride. (J Vasc Surg 2002;36:1027-30.)

Skin flap survival is a significant problem in skin surgery; in particular, inadequate arterial or venous blood supply results in necrosis of the distalmost portion. The aim of this study was to evaluate the ability of Vascular Endothelial Growth Factor (VEGF) of modifying the morphological features of skin flaps. Bilateral epigastric skin flaps were raised in 16 Wistar male rats. The epigastric artery and vein of the left flaps were clamped and then injected with rhVEGF (8 rats) or saline (8 rats). The right flaps were not clamped and received rhVEGF or saline systemically. The rats were euthanized on the seventh day and flap skin samples collected. Tissue fragments were subject to immunohistochemical (rhVEGF, VEGFr, VIII factor, CD34 antibodies), ultrastructural and morphostructural investigations. The results showed that rhVEGF improved the condition of flaps and that systemic administration was effective in promoting the development of an adequate vascular network.

The aim of our study is to investigate the effects of chronic sacral neuromodulation on Nitric Oxide (NO) metabolism in the rat bladder. 26 female Sprangue-Dawley rats were considered: group I, normal control rats; group II, a sham treatment, in whom catheters for electrical stimulation were placed in the S1 foramen bilaterally and left in place for 21 days, without performing neuromodulation; group III in whom electrical sacral neuromodulation was performed for 21 days. Finally a cystectomy was performed and the bladder biopsy specimens were sent for immunostaining with n-NOS and i-NOS. Morphological and immunohistochemical analysis was carried out, and evaluated in urothelial cells, endothelial cells and muscle fibers of the muscularis propria. Differences between the 3 groups were analyzed by Student Newman-Keuls test. We could observe that urothelial and endothelial i-NOS (37.00±4.69 and 59.00±7.42 respectively) and urothelial n-NOS (36.80±7.85) expression are significantly increased in neuromodulated rats, compared to groups 1 and 2 (p < 0.005). In conclusion, the increase of i-NOS expression on endothelial cells after sacral neuromodulation could be in some way related to angiogenetic responses in the microvascular structures; the increase of n-NOS and i-NOS expression on urothelial cells can suggest that NO is able to influence the plasticity of bladder response, inducing the release of messengers within the urothelium. This study can therefore improve our understanding of the mechanisms of sacral neuromodulation on chronic bladder dysfunction; further studies will need to better demonstrate the role of angiogenesis in the bladder after sacral neuromodulation and to investigate the effects of neuromodulation in rats with chronically induced bladder dysfunction.